通过温度场数值模拟分析窄间隙埋弧焊过热区组织演化

多层多道焊时,后层焊道的热量会对前层焊道起到热处理的作用,使前层焊道的热影响区组织尤其是过热区组织发生转变,进而改变接头的力学性能.文中采用数值模拟技术,从温度场与组织转变对应关系的角度分析特定焊接工艺下的单丝、双丝窄间隙埋弧焊坡口侧壁过热粗晶区的组织演化过程.模拟结果表明,针对两种焊接形式,焊道厚度为4 mm时,单丝焊原过热区约有50%最终经历正火作用,双丝焊约有55%~60%.针对双丝焊前后焊丝的不同作用,改变焊接工艺,适当降低前丝焊接电流,可以获得更小的坡口侧壁过热粗晶区,并且后层焊道对前层焊道的热处理效果更好.

Numerical analysis of microstructure evolution of coarse grained zone in sidewall during narrow gap submerged arc welding

During the multi-layer and multi-pass welding, the heat affected zone, especially the original coarse grained zone beyond the fusion line, will be heat affected by subsequent welding beads. And the mechanical property will be promoted. This article adopts the numerical simulation technology to analyze the microstructure evolution of coarse grained zone during the single and tandem wires narrow gap submerged arc welding. Simulation results show that, if weld thickness is 4 mm, 50% of the original coarse grain zone becomes fine grained during the single wire welding and 55%~60% of the original coarse grained zone becomes fine grained during the tandem wires welding. Reducing the leading wire''s heat input can obtain more smaller coarse grained zone.